Pulsed Plasma Chamber in Dual Chamber Configuration

Abstract

Embodiments for processing a substrate in a pulsed plasma chamber are provided. A processing apparatus with two chambers, separated by a plate fluidly connecting the chambers, includes a continuous wave (CW) controller, a pulse controller, and a system controller. The CW controller sets the voltage and the frequency for a first radio frequency (RF) power source coupled to a top electrode. The pulse controller is operable to set voltage, frequency, ON-period duration, and OFF-period duration for a pulsed RF signal generated by a second RF power source coupled to the bottom electrode. The system controller is operable to set parameters to regulate the flow of species between the chambers to assist in the negative-ion etching, to neutralize excessive positive charge on the wafer surface during afterglow in the OFF period, and to assist in the re-striking of the bottom plasma during the ON period.

1 . A wafer processing apparatus with a top chamber and a bottom chamber separated by a plate that fluidly connects the top chamber to the bottom chamber, comprising:
 a continuous wave (CW) controller operable to set a voltage and a frequency for a first radio frequency (RF) power source coupled to a top electrode in the top chamber;   a pulse controller operable to set voltage, frequency, ON-period duration, and OFF-period duration for a pulsed RF signal generated by a second RF power source coupled to a bottom electrode in the bottom chamber; and   a system controller operable to set parameters for the CW controller and the pulse controller to regulate a flow of species from the top chamber to the bottom chamber through the plate during operation of the chamber, wherein the flow of species assists in a negative-ion etching and in neutralizing excessive positive charge on the wafer surface during afterglow in the OFF period, and assists in re-striking a plasma in the bottom chamber during the ON period.   
     
     
         2 . The wafer processing apparatus as recited in  claim 1 , wherein the system controller is further operable to set a first pressure in the top chamber and a second pressure in the bottom chamber, and wherein the first pressure is higher than the second pressure. 
     
     
         3 . The wafer processing apparatus as recited in  claim 2 , wherein a duration of the ON period is different from a duration of the OFF period. 
     
     
         4 . The wafer processing apparatus as recited in  claim 2 , wherein a duration of the ON period is equal to a duration of the OFF period. 
     
     
         5 . The wafer processing apparatus as recited in  claim 1 , wherein a frequency of the first RF power source has a value between 27 MHz and 100 MHz. 
     
     
         6 . The wafer processing apparatus as recited in  claim 1 , wherein a frequency of the second RF power source has a value between 0.4 MHz and 25 MHz. 
     
     
         7 . The wafer processing apparatus as recited in  claim 1 , wherein a voltage of the first RF power source has a value between 100 V and 600 V. 
     
     
         8 . The wafer processing apparatus as recited in  claim 1 , wherein a voltage of the second RF power source has a value between 1000 V and 6000 V. 
     
     
         9 . The wafer processing apparatus as recited in  claim 1 , wherein the top chamber is operable to form a top plasma in the top chamber while processing the wafer. 
     
     
         10 . The wafer processing apparatus as recited in  claim 1 , wherein the top chamber is operable to have a first pressure between 20 mTorr and 60 mTorr during processing, and wherein the bottom chamber is operable to have a second pressure between 10 mTorr and 19 mTorr during processing. 
     
     
         11 . A method for processing a wafer in a wafer processing apparatus with a top chamber and a bottom chamber separated by a plate that fluidly connects the top chamber to the bottom chamber, the method comprising:
 setting first parameters for a continuous radio frequency (RF) signal generated by a first RF power source coupled to a top electrode in the top chamber, wherein the first parameters include a first voltage and a first frequency;   setting second parameters for a pulsed RF signal generated by a second RF power source coupled to a bottom electrode in the bottom chamber, wherein the second parameters include a second voltage, a second frequency, ON-period duration, and OFF-period duration;   applying the continuous RF signal to the top electrode; and   applying the pulsed RF signal to the bottom electrode, wherein setting the first parameters and the second parameters regulates a flow of species from the top chamber to the bottom chamber during operation of the chamber, wherein the flow of species assists in a negative-ion etching and in neutralizing excessive positive charge on the wafer surface during afterglow in the OFF-period, and assists in re-striking a plasma in the bottom chamber during the ON period.   
     
     
         12 . The method as recited in  claim 11  further including:
 setting a first pressure in the top chamber; and 
 setting a second pressure in the bottom chamber. 
 
     
     
         13 . The method as recited in  claim 12 , further including:
 increasing the first pressure to increase the flow of species from the top chamber to the bottom chamber.   
     
     
         14 . The method as recited in  claim 11  further including:
 adjusting a length of through-holes in the plate separating the top chamber and the bottom chamber, wherein decreasing the length of the through-holes increases the flow of species from the top chamber to the bottom chamber. 
 
     
     
         15 . The method as recited in  claim 14  further including:
 reducing a number of the through-holes in the plate to decrease the flow of species between the top chamber and bottom chamber. 
 
     
     
         16 . The method as recited in  claim 11 , wherein setting the first parameters includes:
 increasing the first voltage to increase the flow of species.   
     
     
         17 . The method as recited in  claim 11 , wherein operations of the method are performed by a computer program when executed by one or more processors, the computer program being embedded in a non-transitory computer-readable storage medium. 
     
     
         18 . A wafer processing apparatus with a top chamber and a bottom chamber separated by a plate that fluidly connects the top chamber to the bottom chamber, comprising:
 a continuous wave (CW) controller operable to set first parameters for a first radio frequency (RF) power source coupled to a top electrode in the top chamber;   a pulse controller operable to set second parameters for a second pulsed RF signal generated by a second RF power source coupled to a bottom electrode in the bottom chamber, and to set third parameters for a third pulsed RF signal generated by a third RF power source coupled to the bottom electrode; and   a system controller operable to transfer the first, second, and third parameters to regulate a flow of species from the top chamber to the bottom chamber through the plate during operation of the chamber, wherein the flow of species assists in a negative-ion etching and in neutralizing excessive positive charge on the wafer surface during afterglow in the OFF period, and assists in re-striking a plasma in the bottom chamber during the ON period.   
     
     
         19 . The wafer processing apparatus as recited in  claim 18 , wherein the first RF power source has a frequency between 30 MHz and 100 MHz, the second RF power source has a frequency between 0.4 MHz and 4 MHz, and the third RF power source has a frequency between 20 MHz and 100 MHz. 
     
     
         20 . The wafer processing apparatus as recited in  claim 18 , wherein the top chamber is operable to have a first pressure between 20 mTorr and 60 mTorr during processing, and wherein the bottom chamber is operable to have a second pressure between 10 mTorr and 19 mTorr during processing.